Communications transmission facilities typically require an antenna through which the communications signal, such as a radio or television signal, is transmitted and received. Usually, this antenna is mounted at the top of an outdoor transmission tower. Coaxial cable is typically used to carry the communications signal from the communications transmitter/receiver to the antenna on top of the tower.
As will be appreciated, such towers and antennas are subject to being struck by lightning or electrified with respect to earth by inductive coupling to overhead discharges. If lightning does strike a radio transmission tower, voltage from the electric shock will usually be transmitted through the tower, and through any of the coaxial cables extending up the tower between the antenna and the transmitter/receiver.
Design engineers and professional communication consultants have known and advised for many years that one of the most important and useful features of a communications tower installation is direct, low inductance grounding of the coaxial line shields. Lightning/EMP protection, receiver noise reduction, transmitter interference leakage, and poor shield integrity are all problems which can occur if a coaxial transmission line is not grounded properly.
Several commercial products exist for dealing with the problems caused by lightning strikes of antenna towers.
For example, the assignee of the instant application, Industrial Communications Engineers, Ltd., manufactures several coaxial lightning/EMP suppressors which are designed to constantly short circuit and shunt voltage transients caused by lightning, power line induction, wind, rain, snow and various types of explosive releases.
Additionally, the assignee manufactures rotor cable transient voltage suppressors and RF bypass units, ground hub kits, and guy wire compression grounding kits. Rotor cable transient voltage suppressors and RF bypass units are provided to discharge voltage charges of any polarity and origin, and include rapid firing MOV pulse suppressors across each circuit.
Ground hub kits provide a compressive connection for mounting directly to ground rod tops to provide connection points for ground wires leading from the ground rod tops. Guy wire compression grounding kits are typically coupled to guy wires used to support the tower, and are designed to preserve earth-neutral integrity, reduce receiver noise, and help to prevent reradiation or rectification of transmitted signals. Typically, the guy wire compression grounding kits comprise a block having a first bore attachable to the guy wire, and a second bore attachable to a grounding wire.
The patent literature also includes examples of various grounding devices.
Alexander, Jr. published United States Statutory Invention Registration No. H379 relates to a combination strain relief and ground connection for a shielded cable. The Alexander device comprises a two member device molded from an ABS/polycarbonate polymer, or a NORYL or TREVEX polycarbonate copolymers. The two members of the Alexander device are attached by sonic welding. Channels are formed in the exterior of the housing members to enable the device to be received by a notch of an electrically grounded chasis.
Haws U.S. Pat. No. 3,852,700 relates to a grounding base for a connector which is adaptable to be placed between a plug and a socket. The conductor base shown in Haws comprises a generally planar sheet having a plurality of apertures through which the prongs of a plug can extend.
Grabbe U.S. Pat. No. 4,653,840 relates to an electrical connection for four shielded coaxial conductors. The Grabbe device includes a pair of housing blocks that must have conducting surfaces, and can be made of metal if desired. A compressing block is placed between the two housing blocks, and is provided for mating the core conductors of a pair of coaxial cables. The Grabbe device is illustrative of one of the prior art situations the applicants device seeks to overcome in that one of the functions of Grabbe's compression block is to build a good splice between a pair of coaxial cables.
It is therefore one object of the present invention to provide a device for grounding coaxial cables without the need to interrupt the cable by splicing.